Shock absorber for landing gears of airplanes



Patented Dec. 16, 1930 New nLLIo'r Dumm or-ronnnsnain PENNSYLVANIA,assIeNon ro'xnrsronn un.

t curr companion,".'or-nnrsron; PENNsYLvALNIn, n-conronarrorr or DELA.-4

WARE' snocx `russ('Jlilairlisr, non mnnmemsorainnnairns" iappiiesulsfnleiiaugm 2o, reas. sealinaeoovva t Y' :This inventionrelates to landing gear yfor airplanes,` but more articularlyltoishocklv absorbers therefor, an Y the inventionfhasfor its objecttoprovidez'im rovements, in ,theV 5 construction of `these,deviceswhereby great strength ,is :combinedwithr simplicity andv light weight.

Afurther objectiofthe invention to pro-'f 4 vide a=construction wherebytheresiliencyof2 10 the shock absorber propressivelyfdiminishes as' themovement of the piston` increases progressively 4in such manner thatgthedevice, while freely responsive to slight shocks, roperly resists theapplication of-fheavy `s ocks 15 without excessive movement andrebound.'

`These objects are accomplished by iaiconf; struction free ofcomplicatlomand by? an ar-V rangement V01': parts resulting in afcompactunit which is strong, durable and eiiicient. 2 Referring to theaccompanying drawings:

`Figure lis an. elevation -vofithe shock ab\v sorber partly in verticalsection, 'and `1 v;

Y Figure 2 is a transverse sectional view taken` f2s on line 27--2ofFigureL'f Like numeralsof reference indicate the same parts throughoutthe several figures, in

which 1 indicates the'device which* includes the cylinder 2 andpiston-3. y

'3"6 The cylinder 2 receives the tube which leads to the `wheel andaxlemounting ofthe landing'gear, while the piston 2 has a-.pi'ston-' rod 5carrying a fixture. 6 for connection to the structure of theairplane. fj, y. i 3'5 i A'Thetop of the cylinder 2 is suitably flanged at 7 toreceive theiiange 8 ofthe pistonlhe'ad 9, which flanges 7 and 8 areyremovablyj'se` cured to ether as by bolts 10 clamping a'suiti able= pang11 disposed between the said d flanges to provideapressuretight-joint. li l y The cylinder-head 9'i`s provided'with'abore 12 throu lh which ftheplstonrodl extends,"

` and said A ad 'is faced at`13 to receive apafcking'gland 14 by whichthe pistonfrodg may :i5 be suitably packed inthe usual IruirrnelV lReferring particularly to the pis' ,or'r`2?,iii;4v will be seen'thatthesame embodies a `11am pistonhead l'having acentral bell shaped Y,opening 16, andra win ,beseen that the 'wa11,.

"50 of the piston-rod 5 directlyabove the piston..

piston 3, soithat 1communication between the contents fof, the cylinder`onboth sides ofthe tained;` 1.

, piston 15 -isat all times established and main-l it willbe seenuthatitl accommodates therein,`

Iteferringiy ch communicate end21'ilyinglwith1nthe centralbellshapedopening 16 inthe piston-headV 15V, whilethe lower end of, l the taperedli metering pin `,20`

vf provides Van enlargement`22-Qto` receive and centerthe. largeSpiral.` Springy 23 On the lower head24{of the cylinder.2.f Afspringc'enter'-, ing boss 25, is provided onthe plstonhad 15 to :receivetheuppervendofsthervspring 23, as Shown in the drawingr f Having `husvdescribed ,the several parts of the invention its operationi's'a'sfollows: ,f The .parts being assembled, as shown and` eisv described,andthe cylinder 2 Ahaving vbeen filled-with'a suitable luid'such as oil,the

spring 23 is Vof such-l capacityas to sustain the loadffof the airplane,and maintain the piston'3 ian intermediateyposition within the, ncylinder, Upon the application y of an upward thrust on the tube 4andvcylinder 2;

asin landing .the airplane, the piston 3 com# presses the ,spring 23 andmoves inwardly 0f thecy1inder'2, This movement of the piston e`displaces thefjfluid within the' cylinder: 2

through the centralbell shaped opening 16 inthe istonjhead-15 aroundthetapered end 21 of t e taperedmetering in 20, and causes .said luidftopass throu ht e small openings,l

or ports 17 into the c inderspace 19 above Athe piston 3.A Upont erebound'oi`V theipis-vvv ton, the Huid reverses itsigw to establish its`normalfpositon, butas,freedom-` ofthis How -is restricted by rthesizeofithe orts`117, the s eed v,ofthe rebound is suitajly ,checkedy n' thismanner `fthe' desired. resiliency is obgl tainedk under the infiuenceofAlight shocks.

rIt is characteristic offthis structure; that the piston 8isimperforateexcept forthe central bell A shapedl `openinv 16, theeffective area of hich is always uner the control of nmA 'onesideof thepiston to moves inwardly of t e cylinder, and :gradu-y ally facilitatedby the metering pin as the piston moves outwardl of the'cylinder. 'Thepiston includinga plstonrod for connection effect of this is that-t ereis'never any `suddenoutward; movement of the piston Bwhen the inwardmovementis checked. f

When, however, the-shockszis excessive and the spring 23 is subjectedtoa load which wouldimpart excessive movement @of the pis# ton withinthe cylinder, the displacement of the fluid fromunder thepiston isautomati-l cally "and progressively restricted as thev movement of theVvpiston progresses@ This is accomplished bythe action of theyl taperedmetering pin J20, for as'the'pistonpasses down over the metering pin,the'cross sectional ar'eaofthe metering pin increases' as f theAmovement of the piston` progresses, land 'the bell'shaped openingthroughthe pistonf head-around the meteringpin20conseque`ntlydimfinishes progressively. i The'- rate -of the e 1splacement of' the fluid through thepis'ton vijsfprogr'essivelydiminished, and the-move:

ment `of the piston is pro efssively checked.

Were it not for the small ports 17,'thefr`ebound of the pistonunderftheseconditions wouldl be violent, as onthe reverse movement A`nfv the same,-the`area ofthe openingin the piston-headwould beprogresslvelyv increasing and the resistance diminishing ,whichV wouldte'nd to'accellerate the speed of therebound. `But the small ports17-prevent such result. The :area'of said ports are iixed and thereforerestrict too rapid displacement of' the kiiuid from aboveboundmove'ment. Q Iprefer to shape'the the piston on its vre-v orifice164 'substantially as an inverted bellso as to-'contract-thev oilstreamin an upward directionor Iwhen the? piston is moving underthe'influence of 1 durablev and-free from likelihoodcf ibrealr#l the drawingiandfslierein described; as the" shoe 4and tolinsure an easier butfnotla sudden flow of oil inthe 'reverse' directionv when the piston isrebounding so as to effect 4a suiiciently quick but not a suddenrecovery.

" VIt will then bev seen that the inventivepui' pose of -theV device is:accomplished: inV a particularly` simple and effective manner`,and"witlioutfcomplication':of parts, but by theuse-of anv assembly`which is robust and Having fuuy fetes'cannedA he-intention, a' 'is tdbeunderstoodv that the same is not to be limited' toy the exact`construction shown 'fin same'iis susceptible '5to changes in the con#structioni and'larrangement'of parts, and it is considered thatftheinvention clearly embraces all of suchffchanges Vandv modifications Vtoan'fairplane structure, lthe said pistonbe- 'ing restricted 'to acentral opening in its head and havingga plurality of small portsv abovethe piston head, and having a chamber communicating with 'said smallports and open to the cylinder above thepiston to establish and maintaincommunication between the r`contents of 'the' cylinderl on' both sidesof the pistonv at all times, a tapered? metering pin within tlie'saidcylinder, Y'having its -upper end extending throughthe/said centralopening inthe-'piston head to provide a s ace around the tapered studvto control disp acement of a fluid through piston head upon moyen'aent`off'tliepi'ston in thefcylinder in either "direction, and a springwithin the cyl-` inder and under the piston to-'normallyholdl theVpiston lin o erative' position, the 'whole arranged where y upon'inwardmovement cf the-piston in the cylinder 'and along thetaperedmetering'pin, the displacement of fluid elow `the pistonfheadisprogressively restricted by the progressively diminishino` area of .thespace'in the ypiston-head around the tapered kmetering pin Iand uponoutward movement of the piston in the cylinder, va rapid displacementofthe Huid from above the piston is restricted bythe said'srnallportsaboveY the piston. Y M i 2. A device of the character describedincluding a cylinder and a ypiston yand means for connection with thelanding l"gear of an airplane, the piston vincluding apistonrod andbeing restricted to a central `opening in itshead and a "luralityofsmall ports above the pistonhead) I municating withlsaid small ports andopeninofto the cylinder above they piston to establis and maintaincommunication between the contents of the cylinderl on both sides of thepiston atalll timesga taperedmetering pin withinthe saidcylinder havingits upper end extending 'through the said central openin c inthepiston-'head toprovide a spacearoun the taperedmetering lpin to controldisplacecylinder and under the piston to normally hold ther `piston in oerative; position, thel whole arranged where y upon inward movementofthe piston in thecylinder and; along the tapered metering pin, thedisplacement ofthe fluid below the piston-head is progressively"restricted byfprogressively dlminish? and havinga chamber com` ing areaof theV space in the piston-head around the tapered metering pin,flanduplon outward movement of the pistonin-th'e c 'nv der, a rapiddisplacement ofc-the Huid rom p 5 above the piston is restricted bythesaid small ports above the piston. n 3. A device of,7 hecharacterdescribed including a cylinder and a iston, `the latter includin apiston-rod and eing restricted toa lo centraopening initshead and aplurality of small ports, above'the iston head' communicatin with thecylin" er above the'piston to esta lish and maintain communicationbetween the contents of the cylinder on both -4 sides ofthe piston atalltimes, a taperedme- 1 f .tering in within the cylinder having its upiper end) extendingthrou h the .said central n opening in the piston-heato provide'aspace around the tapered metering" in tocontrol Agodisplacement of fluid throng said piston head upon movement ofthe piston1n the ,e cylinder in either direction, and a y'spring p y within the Ycylinder and under the pistoni to `normally ho d the piston'in operatlveposi- A 'tion, `the' whole arranged for operation 4as specified in claim2; Y o Y i p 4. A device of the character described inl cluding acylinder and a piston, the lattei` y v including a piston-rod restrictedto a single ao central opening in its head to permit displacement of a-iiuid therethrough and having means above the piston f or assistinginrestricting the dis lacement of a fluidthrou'gh the piston to esta lishand maintain communia5 catlon between the contents of the cylinder onboth sides of the iston atv all times, a tapered metering in wit in the'cylinder having its upper en extending throughthe said-opening in the`piston-head tov provide a" s ace 40 around the tapered metering pin, thew ole arranged in such manner that upon inward movement of the lstoninthe cylinder, 'the' displacement of t e Huid belowA` the `piston ea ispro essively restricted by the progressively dlminishin y area of -thespace in.

the piston head aroun the ta red meterin pin to control displacement oHuid through the piston head in either direction and upon` outwardmovement of the piston in the cylinder, a rapiddisplacement ofthe 'fluidvfrom above the piston is restricted bythe said displacementrestrictingmeans above the piston.

In testimony whereof I aiiix my signature. ELLIOT .DALAND

